Hi Tetsuo,
>> To fix what was addressed in e305509e678b3a4a, defer putting hdev until
>> sock is released with sock locked.
>>
>> Now only for thoughts.
>
> Thanks for your analysis.
>
> hci_alloc_dev() is called from hci_uart_register_dev() from hci_uart_set_proto()
> from hci_uart_tty_ioctl(HCIUARTSETPROTO) via ld->ops->ioctl() from tty_ioctl(),
> and bt_host_release() is called from device_release() from kobject_put() from
> hci_uart_tty_close() from tty_ldisc_kill() from tty_ldisc_release() from
> tty_release_struct() from tty_release() from __fput().
>
> The problem is that bt_host_release() is expecting that hci_register_dev()
> was called if "struct hci_dev" was allocated by hci_alloc_dev(). In other
> words, hci_register_dev() might not be called before bt_host_release().
>
> Then, the fix I think is not to call hci_release_dev() when hci_unregister_dev()
> was not called. That is,
>
> static void bt_host_release(struct device *dev)
> {
> struct hci_dev *hdev = to_hci_dev(dev);
> +
> + if (hci_dev_test_flag(hdev, HCI_UNREGISTER))
> + hci_release_dev(hdev);
> kfree(hdev);
> module_put(THIS_MODULE);
> }
>
> and remove kfree(hdev) from hci_release_dev(), for HCI_UNREGISTER flag is
> set if hci_unregister_dev() was called before bt_host_release() is called.
actually I am wondering if we should just remove the HCI LDISC support. All the tests
are focusing around the fact that you can create a line discipline as unprivileged
user.
To be honest the HCI LDISC support is not in use anymore for anything deployed after
we got around to establish TTY serdev support.
I am worried that we are trying hard to fix something in the Bluetooth core that
is actually a bug in the hci_uart driver and should be fixed solely there. Or that
driver needs to be deprecated. Are other drivers and their lifetime rules also
exhibiting these issues?
Regards
Marcel
